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Assignment 1 Unit 9 - Environmental Forensics
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Unit 9 Assignment A- Bugs and DecompositionAsh Baish
Types of Injuries
Post-mortem injuries happen after death. These are most commonly pseudo-trauma injuries.
However, these could also be wounds that happened after the victim died and the perpetration just
did not stop injuring the victim until they knew the victim was dead.
Peri-mortem injuries happen during death. These are most commonly blunt or sharp-force trauma
which causes the fatal injury to the body.
Ante-mortem injuries happen before death. These types of injuries have usually begun to heal
before the death has occurred. These are things like arthritis damage, previous breaks, or fractures
to bones.
Pseudo-trauma is when animals in the area interact with the body through eating, scratching, or
other actions, which disturb the tissue and bone, but these disturbances are unrelated to the cause
of death.
Blunt-force trauma is where a victim is hit with a blunt object with severe force which causes
damage to the victim’s bone and tissue.
Sharp-force trauma is where a victim is hit with a sharp object with severe force which causes
damage to the victim’s bone and tissue.
The post-mortem stages of death
There are four stages of mortis (death) that happen post-mortem. These are pallor mortis, rigor
mortis, algor mortis, and livor mortis. These are what happens to the body after it dies, but before
the body starts to decompose.
Pallor Mortis (pale death) is where the body’s blood stops flowing to the skin, giving the body a paler
appearance. This usually appears quite soon after death as when the blood stops circulating around
the body, it begins pallor mortis immediately. When coming across a body which is in its pallor
mortis stage, this usually means that you have found them in the first few minutes of death.
Rigor Mortis (rigid death) is where the body becomes rigid. This happens because the body has
already shut down and you have stopped using all your limbs, so they stiffen and solidify causing the
body to be stuck in the position it died in. This usually sets in soon after death and lasts 2-3 days
before the body can be handled again.
Algor Mortis (cold death) is where the body begins to cool down, the rate at which this happens
depends on the conditions the body is in. However, everybody begins to cool down after death, no
matter the conditions, the rate of cooling is what changes. The rate of cooling depends on the body’s
environment because if the body is already cold and in a cold environment, it would cool slower
than a body which was warmer, as this environment preserves a body. Whereas, in a warmer
environment, the body’s temperature could either be kept around the same temperature (this is
most likely to happen in a jungle or rainforest) or the body would be extremely burnt on the outside
(this is most likely to happen in a desert). This depends on how warm the environment is.
, Livor Mortis (Bluish death) is where the blood begins to ‘pool’ in one part of the body, due to gravity.
This is also called hypostasis, lividity, or ‘marbling.’ This ‘pooling’ of blood causes a bluish
discolouration to the body’s skin, so after livor mortis has taken place, we can see where the gravity
pulled the blood to. This can tell us what position the body was in when the blood began to ‘pool’
which can tell us whether the body was moved and possibly, how the body died. This happens 3-4
hours post-mortem.
Stages of decomposition
There are five stages of decomposition. This begins with the body breaking down from the inside out
and ends with the body with nothing left apart from the bones. When the body is in the final stage
of decomposition, they body becomes human remains as it’s only the bones left, there is not a body.
Stage 1:
Autolysis is the first stage of decomposition where the cells in the body break down on their own.
Autolysis means automatic cell rupture. This tells us that it is where the body begins to eat itself.
This begins at between 24- and 72-hours post-mortem. Because within the first 4 minutes of death
the oxygen (O2) stops circulating the body, the Carbon dioxide (CO2) begins to build up as it cannot
be released. This leads to the pH in the body dropping, meaning that the body becomes more acidic.
This cell break-down happens because the bacteria present in the stomach and other natural
microflora that are not Indigenous all start to multiply in the body, and release gases and enzymes
which then cause the cells to rupture. The enzymes released from these bacteria and microflora
then begin to eat the body’s tissue from the inside to the outside.
At this stage, there are no Detritivores present as the putrefaction has not started to be released
from the body. This is because the microorganisms have not yet released their gases that cause the
putrefaction smell, so the detritivores do not think the body is ready to eat yet.
Stage 2:
Bloating is the second stage of decomposition where the cells in the body release gases, which then
causes the body to begin to bloat. This happens between 2 to 6 days post-mortem. It is at this stage
where the body begins to release the putrefaction scent that attracts detritivores (e.g., maggots,
beetles, and worms). This putrefaction scent is caused by the gases released from the
microorganisms. The typical gases released are methane, CO2, ammonia, and Hydrogen Sulphide.
This putrefaction makes the body smell like rubbish or rubbish bins. This bloating leads the body to
be double its size. Saprophytic activity can also occur at this stage. This is activity of funguses and
moulds on the body, this is where the funguses begin to eat parts of the body, in the same way that
maggots and beetles do. The detritivores and saprophytic activity will speed up the decomposition
process, as they feast on the body’s tissue, which is already decaying, which causes the outer layers
of skin to slip, if the seams have not already burst due to bloating. The body’s hair will eventually
separate from the body too.
At this stage, insect activity begins. The early-stage decomposition Diptera now begin to lay eggs on
any openings or crevices in the body (this could be wounds, or any natural crevices like the mouth,
anus, eyes etc.). After around 24-hours, the eggs begin to hatch and enter into the body. However,
due to the life cycle of these flies, it can take between two to three weeks for a fly egg to turn into a
larva (maggot/s), and then a fly. This time range is different for different Diptera species, and the
temperature of the body and its surroundings can also affect the timing.
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